KLox

This is the interpreter of KLox, a toy language based on Lox, as described by the book Crafting Interpreters by Bob Nystrom. KLox is quite different from Lox, but the overall structure of the interpreter is still very similar.

Features include:

• type inference
• const variables
• lexical scope

Operators

+, -, /, *, %, +=, -=, *=, /=, %=, !, &&, ||, >, <, <=, >=, ==, !=, ??, ??=, ? :, between and

Keywords

for, while, loop, if, else, break, continue, return, var, const, fun, debug

Types

KLox is statically typed and supports string, number, bool and nil as primitives. nil is currently a separate type, and other types cannot be nil. This will change once I add polymorphism.

Functions are treated as first-class citizens. Types are globally inferred.

Native functions

• clock()
  returns the current time in milliseconds since jan 1st, 1970
• sleep(milliseconds)
  sleep for the specified number of microseconds
• print(message)
  takes a string and prints it to stdout, appending a newline
• readLine()
  read a line from stdin and return it as a string
• substr(string, start, end)
  retrieve part of a string

var vs. const

There are two keywords to declare variables, var and const. const must be assigned to while declaring while var does not, but both must be assigned to before they can be read. After declaration, variables declared with const can never be assigned to again. Neither var or const can ever be redeclared in the same scope.